till it reached a
distance of 180 degrees from its origin and encircled the earth at its
widest part, after which it continued to advance in a contracting form
until it reached the antipodes of the volcano; whence it was reflected
or reproduced and travelled back again to Krakatoa. Here it was turned
right-about-face and again despatched on its long journey. In this way
it oscillated backward and forward not fewer than six times before
traces of it were lost. We say "traces," because these remarkable facts
were ascertained, tracked, and corroborated by independent barometric
observation in all parts of the earth.

For instance, the passage of the great air-wave from Krakatoa to its
antipodes, and from its antipodes back to Krakatoa, was registered six
times by the automatic barometer at Greenwich. The instrument at Kew
Observatory confirmed the records of Greenwich, and so did the
barometers of other places in the kingdom. Everywhere in Europe also
this fact was corroborated, and in some places even a seventh
oscillation was recorded. The Greenwich record shows that the air-waves
took about thirty-six hours to travel from pole to pole, thus proving
that they travelled at about the rate of ordinary sound-waves, which,
roughly speaking, travel at the rate of between six and seven hundred
miles an hour.

The height of the sea-waves that devastated the neighbouring shores,
being variously estimated at from 50 to 135 feet, is sufficiently
accounted for by the intervention of islands and headlands, etcetera,
which, of course, tended to diminish the force, height, and volume of
waves in varying degrees.

These, like the air-waves, were also registered--by self-acting
tide-gauges and by personal observation--all over the world, and the
observations _coincided as to date with the great eruptions of the 26th
and 27th of August_. The influence of the sea-waves was observed and
noted in the Java sea--which is shallow and where there are innumerable
obstructions--as far as 450 miles, but to the west they swept over the
deep waters of the Indian Ocean on to Cape Horn, and even, it is said,
to the English Channel.

The unusual disturbance of ocean in various places was sufficiently
striking. At Galle, in Ceylon, where the usual rise and fall of the
tide is 2 feet, the master-attendant reports that on the afternoon of
the 27th four remarkable waves were noticed in the port. The last of
these was preceded by an unusual re